Polycarbonate copolymer, resin composition, and molded article

ABSTRACT

There are provided a polycarbonate copolymer (A) which has excellent light resistance and heat resistance and comprises an aromatic dihydroxy component comprising 5 to 95 mol % of fluorene-skeleton-containing dihydroxy compound (1) having a specific structure and 95 to 5 mol % of ordinary bisphenol type dihydroxy compound (2), the content of fluorene-9-one in the copolymer being not higher than 15 ppm; and a polycarbonate composition comprising 0.01 to 5 parts by weight of ultraviolet absorber (B) based on 100 parts by weight of the copolymer (A), and the composition comprising the copolymer.

TECHNICAL FIELD

The present invention relates to a polycarbonate copolymer, and a resincomposition and molded article comprising the copolymer. Morespecifically, it relates to a polycarbonate copolymer having excellentlight resistance and heat resistance, a resin composition comprising thecopolymer, and a molded article formed therefrom.

Much more specifically, it relates to a polycarbonate copolymer capableof providing a molded article which is excellent not only intransparency but also in color stability under a high temperatureatmosphere and light resistance, a resin composition comprising thecopolymer, and use of the composition to a molded article.

BACKGROUND ART

A polycarbonate resin obtained by reacting bisphenol A with a carbonateprecursor has heretofore been widely used in many fields as anengineering plastic due to its excellent transparency, heat resistance,mechanical properties and dimensional stability. Due to the excellenttransparency in particular, it is used in many applications as anoptical material, and its use in such applications requiring heatresistance as light covers, gloves, electronic component materials, LEDlenses, prisms, hard disk carriers, films for liquid crystal substratesof liquid crystal displays and retardation films has been considered inrecent years. In the case of these applications, the ordinarypolycarbonate resin obtained from bisphenol A has a problem. Forinstance, when it is used in the film for a liquid crystal display, ithas a problem of insufficient heat resistance because a high temperaturetreatment of 180° C. or higher is required in an oriented film formationprocess, electrode formation process or the like. Further, when theconventional polycarbonate is used in the light cover or glove, it alsohas a problem in heat resistance due to an increase in heat quantityalong with an increase in luminescence intensity of lights in recentyears.

To improve the heat resistance of the polycarbonate, a method of usingbisphenols having a structure which is bulky and is not easily movableis generally applied, and various polycarbonates have been proposed. Ofthese, polycarbonates having specific fluorene skeletons have beenproposed (for example, JP-A 6-25401 (the term “JP-A” as used hereinmeans an “unexamined published Japanese patent application”), JP-A7-52271, JP-A 11-174424 and JP-A 11-306823). However, although thesepolycarbonates having fluorene skeletons are excellent in heatresistance, the initial color of articles molded from the polycarbonateshas strong yellowness, so that an improvement in the color is requiredwhen they are used in optical applications or outer coveringapplications.

Further, since the polycarbonates having fluorene skeletons are liableto be degraded and yellowed very easily by irradiation of ultravioletradiation after molded, applications thereof are limited when applied tooptical components or outer covering parts.

Meanwhile, to prevent degradation or yellowing of the ordinarypolycarbonate from bisphenol A by ultraviolet radiation, addition ofbenzotriazole or benzophenone based ultraviolet absorber to the resin(JP-A 11-35815) or addition of benzoxazine-one based ultravioletabsorber to the resin (JP-A 59-12952) has been proposed. Use of theseultraviolet absorbers has an effect of preventing degradation byultraviolet radiation to some extent on articles molded from theordinary polycarbonate from bisphenol A, depending on the type andamount of the absorber. However, since the above polycarbonate having afluorene skeleton has a structure that is easily degraded by ultravioletradiation in addition to having yellowness in the initial color aftermolding as described above, selection of the type and amount of anultraviolet absorber is limited. For example, when an ultravioletabsorber is added to the polycarbonate having a fluorene skeleton in asufficiently large amount to improve light resistance according to itstype, a molded article therefrom may undergo detective moldings orcoloration, or the heat resistance of the resin may deteriorate.

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

Therefore, a first object of the present invention is to improve thecolor in the initial stage of molding of a fluorene-skeleton containingpolycarbonate having relatively good heat resistance and birefringence.

A second object of the present invention is to provide a resin and aresin composition which hardly undergo deterioration and yellowingcaused by ultraviolet radiation, in an article molded from apolycarbonate having a fluorene skeleton.

A third object of the present invention is to provide a resin and aresin composition which very hardly undergo degradation of physicalproperties and deterioration in color when exposed to ultravioletradiation or heat, in an article molded from a polycarbonate having afluorene skeleton.

Another object of the present invention is to provide a molded articleformed from a polycarbonate having a fluorene skeleton and havingexcellent transparency, birefringence, heat resistance, mechanicalproperties and dimensional stability, particularly an optical articlehaving these characteristics.

According to studies made by the present inventors, it has been revealedthat a specific impurity existing in a dihydric phenol raw materialhaving a fluorene skeleton or produced by a side reaction during apolymerization reaction of the dihydric phenol causes initial color inmolding of the polycarbonate having a fluorene skeleton. Morespecifically, when the content of fluorene-9-one existing as an impurityin the polycarbonate obtained by the polymerization reaction is equal toor higher than a certain content, the initial color after molding isdegraded, and it significantly influences deterioration in the physicalproperties of a molded article and yellowing of the molded articlecaused by ultraviolet radiation.

Meanwhile, it has been revealed that to control the content offluorene-9-one in the polycarbonate to lower than the certain content, adihydric phenol having a low fluorene-9-one content should be used asthe dihydric phenol raw material having a fluorene skeleton or adihydric phenol from which fluorene-9-one has been removed bypurification should be used and conditions which do not allow productionof fluorene-9-one by by-product of dihydric phenol during polymerizationshould be used.

Further, according to the studies of the present inventors, it has beenfound that a polycarbonate whose fluorine-9-one content is lower thanthe certain content has advantages that a change in the color of anarticle molded therefrom caused by heat or ultraviolet radiation issmall and that production of fluorene-9-one from the fluorene skeletonis further suppressed by addition of an ultraviolet absorber, inaddition to an advantage of having excellent initial color aftermolding. It is assumed that this is because the content offluorene-9-one in the resin which is lower than the certain content hasan effect of suppressing further production of fluorene-9-one from thefluorene skeleton by heat or ultraviolet radiation.

Means for Solving the Problems

The above objects of the present invention have been achieved based onthe findings.

That is, according to the present invention, there are provided apolycarbonate copolymer (A) which comprises an aromatic dihydroxycomponent, the aromatic dihydroxy component comprising 5 to 95 mol % offluorene-skeleton-containing dihydroxy compound (1) represented by thefollowing general formula [1]:

(wherein R¹ to R⁴ are each independently a hydrogen atom, a hydrocarbongroup with 1 to 9 carbon atoms which may contain an aromatic group, or ahalogen atom.), and 95 to 5 mol % of dihydroxy compound (2) representedby the following general formula [2]:

(wherein R⁵ to R⁸ are each independently a hydrogen atom, a hydrocarbongroup with 1 to 9 carbon atoms which may contain an aromatic group, or ahalogen atom, and W is a single bond, a hydrocarbon group with 1 to 20carbon atoms which may contain an aromatic group or an O, S, SO, SO₂, COor COO group.), the content of fluorene-9-one in the polycarbonatecopolymer being not higher than 15 ppm; and a molded article formed fromthe copolymer.

According to the present invention, there are also provided apolycarbonate composition comprising 100 parts by weight of the abovepolycarbonate copolymer (A) having a fluorene-9-one content of nothigher than 15 ppm and 0.01 to 5 parts by weight of ultraviolet absorber(B); and a molded article formed from the compositions.

Hereinafter, the polycarbonate copolymer of the present invention, theresin composition comprising the copolymer and the molded articlesformed from the copolymer and the composition will be further described.

The aromatic dihydroxy component constituting the polycarbonatecopolymer of the present invention comprises 5 to 95 mol %, preferably10 to 90 mol %, more preferably 15 to 80 mol % of thefluorene-skeleton-containing dihydroxy compound represented by the aboveformula [1]. When the proportion thereof is lower than 5 mol %,unsatisfactory properties as a heat resistant material which is anobject of the present invention result disadvantageously.

The most preferable range of the dihydroxy component represented by theabove formula [1] is 30 to 75 mol %.

In the above formula, R¹ to R⁴ are preferably each independently ahydrogen atom or a methyl group. It is particularly preferred that R¹and R² be a hydrogen atom and R³ and R⁴ be a methyl group.

Illustrative examples of 9,9-bis(4-hydroxyphenyl)fluorenes include9,9-bis(4-hydroxyphenyl)fluorene,9,9-bis(4-hydroxy-3-methylphenyl)fluorene,9,9-bis(4-hydroxy-3-ethylphenyl)fluorene, and9,9-bis(4-hydroxy-2-methylphenyl)fluorene. Of these,9,9-bis(4-hydroxy-3-methylphenyl)fluorene is preferred.

As the dihydroxy component represented by the above general formula [2]and used in the polycarbonate copolymer of the present invention, anydihydroxy compound which is generally used as a dihydroxy component ofan aromatic polycarbonate may be used. Illustrative examples thereofinclude hydroquinone, resorcinol, 4,4′-biphenol,1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane(bisphenol A), 2,2-bis(4-hydroxy-3-methylphenyl)propane (bisphenol C),2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane,1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z),1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane,2,2-bis(4-hydroxyphenyl)pentane,4,4′-(p-phenylenediisopropylidene)diphenol,α,α′-bis(4-hydroxyphenyl)-m-diisopropylbenzene (bisphenol M), and1,1-bis(4-hydroxyphenyl)-4-isopropylcyclohexane. Of these, bisphenol A,bisphenol C, bisphenol Z and bisphenol M are preferred, and bisphenol Ais particularly preferred.

The polycarbonate copolymer preferably shows a specific viscosity at 20°C. of 0.2 to 1.2, more preferably 0.25 to 1.0, much more preferably 0.27to 0.80, when a solution having 0.7 g of the polymer dissolved in 100 mlof methylene chlorine is measured for the specific viscosity. With thespecific viscosity within the above range, a molded article or film issufficiently strong, has adequate melt viscosity and solution viscosityand is easy to handle advantageously.

The polycarbonate copolymer of the present invention is produced byreaction means known per se for producing an ordinary polycarbonate,e.g., a method comprising reacting an aromatic dihydroxy component witha carbonate precursor such as phosgene or a carbonic diester. Next,basic means will be briefly described with respect to the productionmethod.

A reaction using, for example, phosgene as a carbonate precursor isgenerally carried out in the presence of an acid binding agent and asolvent. As the acid binding agent, an alkali metal hydroxide such assodium hydroxide or potassium hydroxide or an amine compound such aspyridine is used. As the solvent, a halogenated hydrocarbon such asmethylene chloride or chlorobenzene is used. Further, a catalyst such asa tertiary amine or a quaternary ammonium salt can be used to acceleratethe reaction. In that case, the reaction temperature is generally 0 to40° C., and the reaction time is several minutes to 5 hours.

An ester exchange reaction using a carbonic diester as a carbonateprecursor is carried out by a method comprising agitating apredetermined amount of an aromatic dihydroxy component together with acarbonic diester under heating in an inert gas atmosphere whiledistilling out an alcohol or phenol produced. Although the reactiontemperature varies according to the boiling point of alcohol or phenolproduced and other factors, it generally ranges from 120° C. to 300° C.The reaction is carried out under reduced pressure from the initialstage and completed while distilling out the alcohol or phenol produced.

Further, to accelerate the above reaction, catalysts which are generallyused in an ester exchange reaction can be used. Specific examples of thecarbonic diester used in the above ester exchange reaction includediphenyl carbonate, dinaphthyl carbonate, bis(diphenyl)carbonate,dimethyl carbonate, diethyl carbonate, and dibutyl carbonate. Of these,diphenyl carbonate is particularly preferred.

In the polymerization reaction of the polycarbonate copolymer of thepresent invention, monofunctional phenols which are generally used as aterminal blocking agent can be used. Particularly, in the case of areaction using phosgene as a carbonate precursor, the monofunctionalphenol is generally used as a terminal blocking agent to adjust amolecular weight, and an obtained aromatic polycarbonate copolymerhaving its terminals blocked by groups based on the monofunctionalphenol has better thermal stability than its counterpart whose terminalsare not blocked by the groups.

The monofunctional phenols may be any monofunctional phenols which areused as a terminal blocking agent for an aromatic polycarbonate resin.They are generally phenols or lower alkyl substituted phenols and can beexemplified by monofunctional phenols represented by the followinggeneral formula:

(wherein A represents a hydrogen atom or a linear or branched alkyl orarylalkyl group having 1 to 9 carbon atoms, and r represents an integerof 1 to 5, preferably 1 to 3.)

Specific examples of the above monofunctional phenols include phenol,p-t-butylphenol, p-cumylphenol and isooctylphenol.

Further, other monofunctional phenols such as phenols or benzoicchlorides having a long-chain alkyl group or aliphatic ester group as asubstituent, and long-chain alkyl carboxylic chlorides can be used. Whenthe aromatic polycarbonate copolymer is terminal-blocked by use of thesemonofunctional phenols, they not only serve as a terminal blocking agentor a molecular weight adjuster but also improve the melt flowability ofthe resin, thereby facilitating molding, and improve its physicalproperties as well. The above monofunctional phenols are preferably usedparticularly because they have an effect of reducing the waterabsorption of the resin. They are represented by the following generalformulae [I-a] to [I-h]:

(wherein X represents —R—O—, —R—CO—O— or —R—O—CO— wherein R represents asingle bond or a divalent aliphatic hydrocarbon group having 1 to 10carbon atoms, preferably 1 to 5 carbon atoms;

-   T represents a single bond or one of the same bonds as those    represented by the above X;-   n represents an integer of 10 to 50;-   Q represents a halogen atom or a monovalent aliphatic hydrocarbon    group having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms;-   p represents an integer of 0 to 4;-   Y represents a divalent aliphatic hydrocarbon group having 1 to 10    carbon atoms, preferably 1 to 5 carbon atoms;-   W¹ represents a hydrogen atom, —CO—R¹⁷, —CO—O—R¹⁸ or R¹⁹ wherein    R¹⁷, R¹⁸ and R¹⁹ each independently represent a monovalent aliphatic    hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 5    carbon atoms, a monovalent alicyclic hydrocarbon group having 4 to 8    carbon atoms, preferably 5 or 6 carbon atoms, or a monovalent    aromatic hydrocarbon group having 6 to 15 carbon atoms, preferably 6    to 12 carbon atoms;-   a represents an integer of 4 to 20, preferably 5 to 10;-   m represents an integer of 1 to 100, preferably 3 to 60,    particularly preferably 4 to 50;-   Z represents a single bond or a divalent aliphatic hydrocarbon group    having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms; and,-   W² represents a hydrogen atom, a monovalent aliphatic hydrocarbon    group having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, a    monovalent alicyclic hydrocarbon group having 4 to 8 carbon atoms,    preferably 5 or 6 carbon atoms, or a monovalent aromatic hydrocarbon    group having 6 to 15 carbon atoms, preferably 6 to 12 carbon atoms.)

Of these, substituted phenols of [I-a] and [I-b] are preferred. As thesubstituted phenols of [I-a], compounds having an n of 10 to 30 arepreferred, and compounds having an n of 10 to 26 are particularlypreferred. Specific examples thereof include decylphenol, dodecylphenol,tetradecylphenol, hexadecylphenol, octadecylphenol, eicosylphenol,docosylphenol and triacontylphenol.

Further, as the substituted phenols of [I-b], compounds in which X is—R—CO—O— and R is a single bond are appropriate. Compounds having an nof 10 to 30 are suitable, and compounds having an n of 10 to 26 areparticularly suitable. Specific examples thereof include decylhydroxybenzoate, dodecyl hydroxybenzoate, tetradecyl hydroxybenzoate,hexadecyl hydroxybenzoate, eicosyl hydroxybenzoate, docosylhydroxybenzoate and triacontyl hydroxybenzoate.

In the substituted phenols or substituted benzoic chlorides representedby the above general formulae [I-a] to [I-g], the positions ofsubstituents are generally preferably a para position or an orthoposition, and a mixture of the two is preferred.

The above monofunctional phenols are desirably introduced to at least 5mol %, preferably at least 10 mol % of all terminals of the obtainedpolycarbonate copolymer. Further, the monofunctional phenols may be usedalone or in admixture of two or more.

Further, when 9,9-bis(4-hydroxyphenyl)fluorenes constitute 60 mol % ormore of all aromatic hydroxy components in the polycarbonate copolymerof the present invention, the flowability of the resin may deteriorate.Accordingly, the substituted phenols or substituted benzoic chloridesrepresented by the above general formulae [I-a] to [I-g] are preferablyused as a terminal blocking agent.

The polycarbonate copolymer of the present invention may be a polyestercarbonate copolymerized with an aromatic dicarboxylic acid such asterephthalic acid, isophthalic acid, naphthalenedicarboxylic acid or aderivative thereof in such an amount that does not impair the effect ofthe present invention. Further, it may also be a branched polycarbonatecopolymerized with a small amount of a trifunctional compound.

The polycarbonate copolymer of the present invention preferably has aglass transition point of 150° C. or higher, more preferably 160° C. orhigher, much more preferably 165 to 210° C.

The polycarbonate copolymer of the present invention preferably has afluorene-9-one content of not higher than 15 ppm, more preferably nothigher than 5 ppm. When the content of fluorene-9-one is higher than 15ppm, a desired aromatic polycarbonate copolymer which has excellentcolor and a very small b value is not obtained disadvantageously.Further, fluorene-9-one can induce deterioration of color when thearomatic polycarbonate copolymer is in a solution state or molten state.From this viewpoint as well, the content of fluorene-9-one should notexceed 15 ppm.

As described above, the aromatic polycarbonate copolymer of the presentinvention is produced by reaction means known per se for producing anordinary aromatic polycarbonate resin, e.g., a method comprisingreacting an aromatic dihydroxy component with a carbonate precursor suchas phosgene or a carbonic diester. However, to obtain the polycarbonatecopolymer of the present invention having a fluorene-9-one content ofnot higher than 15 ppm, various methods and means are desirably employedas described below.

Fluorene-9-one as an impurity in the polycarbonate copolymer is acompound represented by the following chemical formula.

This fluorene-9-one is an impurity which is mixed in or produced fromthe above fluorene-skeleton-containing dihydroxy compound [I] which is araw material for obtaining the polycarbonate copolymer. That is,fluorene-9-one is a compound which is contained as an impurity in thedihydroxy compound [I] as a raw material or by-produced from thecompound [I] during polymerization.

Thus, as the dihydroxy compound [I] as a raw material, one having as lowa fluorene-9-one content as possible should be used. The upper limit ofthe content depends on the copolymerization rate and polymerizationconditions of the dihydroxy compound [I]. In general, a dihydroxycompound [I] having a fluorene-9-one content of not higher than 20 ppm,preferably not higher than 10 ppm, particularly preferably not higherthan 5 ppm should be used as a raw material.

Although a lower content of fluorene-9-one is more preferred, it cannotbe prevented that a small amount of the compound enters thepolycarbonate copolymer from the raw material of the copolymer or fromby-production at the time of hot molding. Therefore, a content of about0.1 ppm or higher cannot be avoided.

It has been revealed that fluorene-9-one not only enters thepolycarbonate copolymer from the raw material but also is produced fromthe dihydroxy compound [I] by a side reaction during polymerization aswell. Thus, for production of the polycarbonate copolymer, conditionswhich minimize by-production of fluorene-9-one from the raw materialdihydroxy compound [I] are desirably selected.

According to studies made by the present inventors, it has been foundthat production of fluorene-9-one during polymerization can besuppressed by (1) a method of limiting a time spanning from dissolvingthe dihydroxy compound in an acid binding agent and a solvent completelyto the start of its reaction with the carbonate precursor to within agiven time and (2) a method of carrying out the reaction between thedihydroxy compound and the carbonate precursor and the polymerizationreaction substantially in the absence of molecular oxygen. Although onlyeither one of these methods may be employed, the effect becomes furtherremarkable when these methods are used in combination. Hereinafter,these methods will be further described.

A reaction using, for example, phosgene as the carbonate precursor isgenerally carried out in the presence of an acid binding agent and asolvent. As the acid binding agent, an alkali metal hydroxide such assodium hydroxide or potassium hydroxide or an amine compound such aspyridine is used. As the solvent, a halogenated hydrocarbon such asmethylene chloride or chlorobenzene is used. Further, a catalyst such asa tertiary amine or a quaternary ammonium salt can be used to acceleratethe reaction. In that case, the reaction temperature is generally 0 to40° C., and the reaction time is several minutes to 5 hours.

In the reaction, a time spanning from dissolving the aromatic dihydroxycompound in the acid binding agent and solvent completely to the startof its reaction with the carbonate precursor is preferably within onehour, more preferably within 30 minutes. When the time to the start ofthe reaction exceeds one hour, the fluorene-skeleton-containingdihydroxy compound [I] is partially decomposed and fluorene-9-one istherefore by-produced, so that the aromatic polycarbonate copolymer ofthe present invention having a low content of fluorene-9-one may not beobtained.

If the above time to the start of the reaction is within one hour, anaromatic dihydroxy compound having a fluorene-9-one content of nothigher than 10 ppm, preferably not higher than 5 ppm, can be used.

Meanwhile, when the content of fluorene-9-one in the aromatic dihydroxycompound is 15 to 25 ppm, the above time to the start of the reaction isdesirably within 5 minutes.

Another method for suppressing by-production of fluorene-9-one is amethod of carrying out the polymerization reaction substantially in theabsence of molecular oxygen. “Substantially in the absence of molecularoxygen” means that molecular oxygen is not allowed to exist in the gasphase and liquid phase in the polymerization reaction system and theoxygen concentration of the gas phase and liquid phase is not higherthan 0.5 ppm, preferably not higher than 0.2 ppm, more preferably nothigher than 0.1 ppm, for example.

To prevent molecular oxygen from existing in the polymerizationreaction, there is employed a method of blowing a nitrogen gas into thepolymerization reaction system or a method of adding a reducing agentsuch as hydrosulfite. A method of sealing it in a reaction containerwith a nitrogen gas is also effective in preventing molecular oxygenfrom entering. Further, it is also effective in suppressingby-production of fluorene-9-one to carry out a purification stepsubsequent to completion of the polymerization reaction in a nitrogengas atmosphere.

As described above, it is known that the polycarbonate having a fluoreneskeleton has improved heat resistance and rigidity. However, thispolycarbonate is apt to be colored by the polymerization reaction aswell as molding, and the color of the resulting molded article has atinge of yellow. Accordingly, the molded article of the polycarbonatehaving a fluorene skeleton has been strongly desired to have its colorimproved for its optical applications.

The above polycarbonate copolymer of the present invention has a verylow content of fluorene-9-one as an impurity and improved color. Thatis, a molded article formed from the polycarbonate copolymer of thepresent invention has very pale yellow, i.e., a very small b value whichwill be described later. Thus, an increase in the utility value ofoptical applications is expected.

Thus, according to the present invention, there is provided apolycarbonate copolymer showing a b value of 5.0 or less when a solutionprepared by dissolving 5 g of the polycarbonate copolymer having afluorene skeleton in 50 ml of methylene chloride in a light blockingcondition is measured at an optical path length of 30 mm.

The b value of the polycarbonate copolymer is a measure of yellowness incolor. As the value becomes smaller, yellow becomes paler. Thepolycarbonate copolymer of the present invention has a b value of 5.0 orless, preferably 4.5 or less, most preferably 3.5 or less. Although thisb value can be achieved by a content of fluorene-9-one in thepolycarbonate copolymer of not higher than 15 ppm, (a) the content ofsulfur or a sulfur compound as an impurity in the copolymer are equal toor lower than a certain content. Alternatively, when (b) a chlorinecontent based on terminal chloroformate groups of the copolymer and aterminal hydroxyl group (OH) content are equal to or lower than certaincontents, the b value of the polycarbonate copolymer molded article canbe made further smaller.

Thus, according to the present invention, there are provided thefollowing polycarbonate copolymers (a) and (b):

-   (a) a fluorene-skeleton-containing polycarbonate copolymer having a    sulfur or sulfur compound content of not higher than 50 ppm in terms    of sulfur atom, and-   (b) a fluorene-skeleton-containing polycarbonate copolymer having a    chlorine content based on terminal chloroformate groups of the    copolymer of not higher than 10 ppm and a terminal hydroxyl group    (OH) content of not higher than 250 ppm.

Only either one of the above conditions (a) and (b) may be satisfied.However, when both of the above conditions (a) and (b) are satisfied,the b value of the polycarbonate copolymer molded article becomesfurther smaller. Further, when the condition (a) or (b) is satisfied,the copolymer has better heat resistance and rigidity.

To reduce the content of sulfur or a sulfur compound as an impurity inthe above condition (a), it is necessary to implement means forpreventing mixing or elution of sulfur or the sulfur compound in theproduction process. For example, when phosgene is produced by using acoke as a raw material, a sulfur component in the coke enters phosgene;thus, it is necessary to use a coke having a low sulfur content orremove a sulfur component produced by subjecting produced carbonmonoxide to an alkaline treatment. Further, when a sulfur-based reducingagent such as hydrosulfite is used to prevent coloration of alkalineaqueous solution of bisphenol, its amount used must be reduced to aminimum required amount. However, in the case of the copolymer of thepresent invention, the above sulfur-based reducing agent must be addedin an excessive amount so as to prevent the coloration; thus, it isnecessary to remove the excessive agent by rinsing with water afteroxidizing it to a water-soluble compound. Further, it is also necessaryto use, as other raw materials used in production of the polycarbonatecopolymer, washing water and materials of packing and the like, thosehaving a low sulfur content and a low possibility of elution of sulfur.

The sulfur compound content of phosgene used in production of thepolycarbonate copolymer is preferably not higher than 5 ppm. The sulfurcompound content is more preferably not higher than 1 ppm, much morepreferably not higher than 0.5 ppm, most preferably not higher than 0.05ppm.

The sulfur compound content of carbon monoxide used in production of theabove phosgene is not higher than 10 ppm, preferably not higher than 5ppm, more preferably not higher than 0.5 ppm.

Carbon monoxide having a sulfur compound content of not higher than 10ppm is obtained by, e.g., a method comprising bringing carbon monoxideobtained by reacting a coke with oxygen into contact with active carbonor active alumina impregnated with a metal oxide and/or metal salt as ofCu, Cr, V, Mo or the like and then bringing the resulting carbonmonoxide into contact with a caustic soda aqueous solution or a methodcomprising bringing the carbon monoxide into contact with a caustic sodaaqueous solution and then bringing the resulting carbon monoxide intocontact with active alumina.

A polycarbonate copolymer which satisfies the above condition (b) has achlorine content based on terminal chloroformate groups of the polymerof not higher than 10 ppm and a content of terminal hydroxyl groups ofthe polymer of not higher than 250 ppm. The chlorine content based onterminal chloroformate groups of the polymer is preferably not higherthan 5 ppm, more preferably not higher than 2 ppm. Further, the contentof terminal hydroxyl groups of the polymer is preferably not higher than200 ppm, more preferably not higher than 100 ppm. When the chlorinecontent based on terminal chloroformate groups of the polymer exceeds 10ppm and the content of terminal hydroxyl groups of the polymer exceeds250 ppm, the color of the polycarbonate copolymer is degraded, metalsare corroded and deterioration of the polycarbonate copolymer ispromoted disadvantageously.

As described above, the polycarbonate copolymer (A) of the presentinvention having a fluorene-9-one content of not higher than 15 ppmforms a mold article which shows excellent color immediately aftermolding and hardly undergoes deterioration or yellowing caused byultraviolet radiation.

According to studies made by the present inventors, it has been revealedthat in a molded article formed from a composition prepared by addingthe ultraviolet absorber (B) to the polycarbonate copolymer (A),production of fluorene-9-one from the fluorene structure in thepolycarbonate copolymer (A) is suppressed, and deterioration oryellowing of the molded article is further suppressed.

Thus, according to the present invention, there are provided apolycarbonate composition comprising 100 parts by weight of thepolycarbonate copolymer (A) having a fluorene-9-one content of nothigher than 15 ppm and 0.001 to 5 parts by weight of the ultravioletabsorber (B) and a molded article formed from the composition.

The above ultraviolet absorber to be added to the polycarbonatecomposition is preferably an ultraviolet absorber which is uniformlydispersible in the polycarbonate resin and is stable under moldingconditions. Particularly, it is preferably one contained in apolycarbonate as an ultraviolet absorber.

As the ultraviolet absorber used in the present invention, abenzotriazole based ultraviolet absorber, a triazine based ultravioletabsorber, a benzoxazine based ultraviolet absorber or a benzophenonebased ultraviolet absorber is used.

Illustrative examples of the benzotriazole based ultraviolet absorberinclude 2-(2′-hydroxy-5′-methylphenyl)benzotriazole,2-(2′-hydroxy-3′-(3″,4″,5″,6″-tetrahydrophthalimidemethyl)-5′-methylphenyl)benzotriazole,2-(2′-hydroxy-3′,5′-di-t-butylphenyl)benzotriazole,2-(2′-hydroxy-5′-t-octylphenyl)benzotriazole,2-(3′-t-butyl-5′-methyl-2′-hydroxyphenyl)-5-chlorobenzotriazole,2,2′-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2-yl)phenol),2-(2′-hydroxy-3′,5′-bis(α,α-dimethylbenzyl)phenyl)-2H-benzotriazole,2-(3′,5′-di-t-amyl-2′-hydroxyphenyl)benzotriazole,5-trifluoromethyl-2-(2-hydroxy-3-(4-methoxy-α-cumyl)-5-t-butylphenyl)-2H-benzotriazole,3-phenyl-7-(4′-methyl-5′-n-butyl-2H-benzotriazole-2-yl) coumarin, and3-phenyl-7-(2H-naphtho[1,2-d]-triazole-2-yl) coumarin.

Of these,2-(2′-hydroxy-3′-(3″,4″,5″,6″-tetrahydrophthalimidemethyl)-5′-methylphenyl)benzotriazole,2-(2′-hydroxy-3′,5′-di-t-butylphenyl)benzotriazole,2-(3′-t-butyl-5′-methyl-2′-hydroxyphenyl)-5-chlorobenzotriazole, and2,2′-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2-yl)phenol)are preferred, and2,2′-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2-yl)phenol)is more preferred.

As the triazine based ultraviolet absorber,2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[(hexyl)oxy]phenol and7-{[4-methoxy-6-(diethylamino)-S-triazine-2-yl]-amino}-3-phenylcoumarinare preferred.

Illustrative examples of the benzoxazine based ultraviolet absorberinclude 2-methyl-3,1-benzoxazine-4-one, 2-butyl-3,1-benzoxazine-4-one,2-phenyl-3,1-benzoxazine-4-one, 2-(1- or2-naphthyl)-3,1-benzoxazine-4-one, 2-(4-biphenyl)-3,1-benzoxazine-4-one,2,2′-bis(3,1-benzoxazine-4-one),2,2′-p-phenylenebis(3,1-benzoxazine-4-one),2,2′-m-phenylenebis(3,1-benzoxazine-4-one),2,2′-(4,4′-diphenylene)bis(3,1-benzoxazine-4-one), 2,2′-(2,6 or1,5-naphthalene)bis(3,1-benzoxazine-4-one) and1,3,5-tris(3,1-benzoxazine-4-one-2-yl)benzene. Of these,2,2′-p-phenylenebis(3,1-benzoxazine-4-one) and2,2′-(4,4′-diphenylene)bis(3,1-benzoxazine-4-one) are preferred.

Illustrative examples of the benzophenone based ultraviolet absorberinclude 2-hydroxy-4-methoxybenzophenone,2-hydroxy-4-n-octoxybenzophenone,2-hydroxy-4-methoxy-2′-carboxybenzophenone, 2,4-dihydroxybenzophenoneand 2,2′-dihydroxy-4-methoxybenzophenone. Of these,2-hydroxy-4-n-octoxybenzophenone is preferred. These ultravioletabsorbers may be used alone or in combination of two or more.

The ultraviolet absorber (B) contained in the polycarbonate compositionof the present invention is particularly suitably an ultravioletabsorber showing an absorbance at 360 nm (A_(360 nm)) measured at anoptical path length of 1 cm of not lower than 0.5 (preferably not lowerthan 0.6) when dissolved in methylene chloride at a concentration of 10mg/L and an absorbance at 400 nm (A_(400 nm)) measured at an opticalpath length of 1 cm of not higher than 0.01 when dissolved in methylenechloride at a concentration of 10 mg/L.

Of the above ultraviolet absorbers (B), the benzoxazine basedultraviolet absorber is suitable. In particular, a benzoxazine basedultraviolet absorber represented by the following general formula [3]:

(wherein R⁹ to R¹¹ each independently represent a hydrogen atom, ahydrocarbon group with 1 to 9 carbon atoms which may contain an aromatichydrocarbon group or a halogen atom, Ar represents a q-valent aromatichydrocarbon group having 6 to 15 carbon atoms, and q represents aninteger of 1, 2 or 3.) is preferred.

Further, when the ultraviolet absorber (B) is added to the polycarbonatecopolymer, it may lower the glass transition temperature of thecopolymer. Thus, the ultraviolet absorber (B) is desirably anultraviolet absorber which does not significantly lower the glasstransition temperature of the copolymer. That is, when the glasstransition temperature of an aromatic polycarbonate resin compositioncontaining 2 parts by weight of the ultraviolet absorber (B) based on100 parts by weight of the polycarbonate copolymer (A) is Tg′ and theglass transition temperature of an aromatic polycarbonate resincontaining no ultraviolet absorber is Tg, Tg−Tg′≦5° C. preferably holds.An ultraviolet absorber which has a low molecular weight or is in aliquid form significantly lowers Tg and severely impairs heat resistancedisadvantageously.

The ultraviolet absorber (B) is contained in an amount of 0.01 to 5.0parts by weight, preferably 0.02 to 3.0 parts by weight, more preferably0.05 to 2.5 parts by weight, based on 100 parts by weight of thepolycarbonate copolymer (A).

The polycarbonate copolymer and polycarbonate composition of the presentinvention may contain various additives used for improving the physicalproperties or moldability of a molded article of a polycarbonate.Illustrative examples of the additives include a thermal stabilizer, anoxidation stabilizer, a mold releasing agent, a bluing agent, acolorant, an antistatic agent, a lubricant, a light diffusing agent anda filler. Further, other polycarbonates and thermoplastic resins mayalso be contained in such a small amount that does not impair the objectof the present invention. Of these additives, specific examples of thethermal stabilizer, antioxidant, mold releasing agent and bluing agentwill be described hereinafter.

(1) Thermal Stabilizer

In the present invention, as a thermal stabilizer, at least onephosphorus compound selected from the group consisting of phosphoricacid, phosphorous acid, phosphonic acid, phosphonous acid and estersthereof may be contained in the polycarbonate copolymer in an amount of0.0001 to 0.05% by weight. By addition of the phosphorus compound, thethermal stability of the polycarbonate copolymer is improved, and adecrease in molecular weight and deterioration of color at the time ofmolding are prevented.

The phosphorus compound is at least one phosphorus compound selectedfrom the group consisting of phosphoric acid, phosphorous acid,phosphonic acid, phosphonous acid and esters thereof. Preferably, it isat least one phosphorus compound selected from the group consisting ofthe following general formulae [4] to [7]:

In the above formulae, R²⁰ to R³¹ each independently represent ahydrogen atom, an alkyl group having 1 to 20 carbon atoms such asmethyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl,hexyl, heptyl, octyl, nonyl, decyl, dodecyl, hexadecyl or octadecyl, anaryl group having 6 to 15 carbon atoms such as phenyl, tolyl ornaphthyl, or an aralkyl group having 7 to 18 carbon atoms such as benzylor phenethyl. Further, when two alkyl groups exist in one compound, thetwo alkyl groups may be bonded to each other to form a ring.

Specific examples of the phosphorus compound represented by the aboveformula [4] include triphenyl phosphate, trisnonylphenyl phosphate,tris(2,4-di-t-butylphenyl)phosphite, tridecyl phosphite, trioctylphosphate, trioctadecyl phosphate, didecyl monophenyl phosphate, dioctylmonophenyl phosphate, diisopropyl monophenyl phosphate, monobutyldiphenyl phosphate, monodecyl diphenyl phosphate, monooctyl diphenylphosphate, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritoldiphosphite, 2,2-methylenebis(4,6-di-t-butylphenyl)octyl phosphate,bis(nonylphenyl)pentaerythritol diphosphite,bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite,bis(2,4-dicumylphenyl)pentaerythritol diphosphite, and distearylpentaerythritol diphosphite. Specific examples of the phosphoruscompound represented by the above formula [5] include tributylphosphate, trimethyl phosphate, triphenyl phosphate, triethyl phosphate,diphenyl monoorthoxenyl phosphate, dibutyl phosphate, dioctyl phosphate,and diisopropyl phosphate. Specific examples of the phosphorus compoundrepresented by the above formula [6] includetetrakis(2,4-di-t-butylphenyl)-4,4-diphenylene phosphonite. Specificexamples of the phosphorus compound represented by the above formula [7]include dimethyl benzene phosphonate, diethyl benzene phosphonate anddipropyl benzene phosphonate. Of these, distearyl pentaerythritoldiphosphite, triethyl phosphate, dimethyl benzene phosphonate andbis(2,4-dicumylphenyl)pentaerythritol diphosphite are preferably used.

The amount of the phosphorus compound is 0.0001 to 0.05 wt %, preferably0.0005 to 0.02 wt %, particularly preferably 0.001 to 0.01 wt %, basedon the polycarbonate copolymer.

Further, in addition to the above phosphorus compounds, benzofuranonebased compounds can also be used as a thermal stabilizer. Specificexamples of the benzofuranone based compounds include5,7-di-t-butyl-3-(3,4-dimethylphenyl)-3H-benzofurano-2-one and5,7-di-t-butyl-3-(2,3-dimethylphenyl)-3H-benzofurano-2-one. Thesecompounds may be used alone or in combination of two or more.

The amount of these compounds is 0.0001 to 5 wt %, preferably 0.001 to0.1 wt %, particularly preferably 0.005 to 0.05 wt %, based on thepolycarbonate copolymer.

(2) Antioxidant

To the polycarbonate copolymer of the present invention can be added acommonly known antioxidant for preventing oxidation. An example of theantioxidant is a phenol based antioxidant. Specific examples thereofinclude triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], pentaerythritol-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate,1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl) benzene,N,N-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamide),3,5-di-t-butyl-4-hydroxy-benzylphosphonate-diethyl ester,tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, and3,9-bis{1,1-dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro(5,5)undecane. A preferred amount of these antioxidants is 0.0001 to0.05 wt % based on the polycarbonate copolymer.

(2) Mold Releasing Agent

Further, to the aromatic polycarbonate copolymer of the presentinvention, a higher fatty acid ester of a monohydric or polyhydricalcohol can be added as a mold releasing agent as required.

The higher fatty acid ester is preferably a partial or full ester of amonohydric or polyhydric alcohol having 1 to 20 carbon atoms and asaturated fatty acid having 10 to 30 carbon atoms. Specific examples ofthe partial or full ester of the monohydric or polyhydric alcohol andthe saturated fatty acid include monoglyceride stearate, monosorbitatestearate, monoglyceride behenate, pentaerythritol monostearate,pentaerythritol tetrastearate, propylene glycol monostearate, stearylstearate, palmityl palmitate, butyl stearate, methyl laurate, isopropylpalmitate, and 2-ethylhexyl stearate. Of these, monoglyceride stearateand pentaerythritol tetrastearate are preferably used.

The amount of the ester of the alcohol and the saturated higher fattyacid is preferably 0.01 to 2 wt %, more preferably 0.015 to 0.5 wt %,much more preferably 0.02 to 0.2 wt %, based on the aromaticpolycarbonate copolymer. When the amount is within this range, thecopolymer shows excellent releasability, and the mold releasing agentdoes not migrate and does not adhere to the surface of metaladvantageously.

(4) Bluing Agent

The polycarbonate copolymer of the present invention may contain abluing agent. Illustrative examples of the bluing agent include MACROLEXVIOLET of Bayer AG, DIARESIN VIOLET and DIARESIN BLUE of MitsubishiChemical Corporation, and TERASOL BLUE of Sand AG. The most suitable isMACROLEX VIOLET. These bluing agents are contained in the polycarbonatecopolymer at a concentration of preferably 0.1 to 3 ppm, more preferably0.3 to 2.5 ppm, most preferably 0.5 to 2.2 ppm.

A composition prepared by adding an ultraviolet absorber to thepolycarbonate copolymer (A) of the present invention can exhibit aneffect of suppressing by-product of fluorene-9-one in the polycarbonatecopolymer (A), and a molded article formed from the composition has highresistance to thermal degradation and yellowing.

Thus, the effect of the ultraviolet absorber (B) is prominently achievedwhen the ultraviolet absorber (B) is contained uniformly in thepolycarbonate copolymer. However, it has been found that the effect ofthe ultraviolet absorber (B) is still attained even when it is coated onthe surface of a molded article of the polycarbonate copolymer as asurface layer.

Thus, according to the present invention, there is also provided amolded article (referred to as a coated molded article) obtained bycoating the surface of a molded article of the polycarbonate copolymer(A) containing 15 ppm or less of fluorene-9-one with a polymer layercontaining the ultraviolet absorber (B).

The thickness of the polymer layer of the coated molded article is 1.0to 50 μm, preferably 2.0 to 20 μm.

The polymer layer which forms the coating layer may contain theultraviolet absorber (B) in an amount of 0.5 to 40 parts by weight,preferably 1 to 35 parts by weight, particularly preferably 5 to 30parts by weight, based on 100 parts by weight of the polymer.Illustrative examples of a method for coating the surface of the moldedarticle with the polymer layer include a method of immersing the moldedarticle in a solution comprising the polymer and the ultravioletabsorber and a method of coating the surface of the molded article withthe solution. The polymer layer to be coated is preferably transparent.Therefore, a transparent polymer is used. Illustrative examples of thepolymer include an acrylic copolymer, a polyolefin and a polyester.Further, a solvent for preparing the polymer solution may be any solventcapable of dissolving the polymer. For example, an alcohol, a ketone, anaromatic hydrocarbon or an aliphatic hydrocarbon is used.

As a method for obtaining a molded article from the polycarbonatecopolymer (A) of the present invention and the composition comprisingthe copolymer, injection molding, compression molding, injectioncompression molding, extrusion molding, blow molding or the like isused. As a method for producing a film or a sheet, a method of producinga film or sheet having an excellent uniform thickness and free fromoptical defects is preferred. Illustrative examples of such a methodinclude solvent casting, melt extrusion and calendering.

The composition of the polycarbonate copolymer of the present inventionsatisfies that when an amount of change in Yellow Index (YI) after a2-mm-thick molded plate formed from a polycarbonate copolymer (A)containing no ultraviolet absorber (B) is exposed to a mercury lamp of300 to 400 nm with an exposure intensity of 15 mW/cm² for 7 days isΔYI₀, a change in Yellow Index after a 2-mm-thick molded plate formedfrom a polycarbonate copolymer composition comprising a predeterminedamount of the ultraviolet absorber (B) used in the present invention isexposed to a mercury lamp of 300 to 400 nm with an exposure intensity of15 mW/cm² for 7 days is ΔYI₁, and the degree (R_(YI)) of lightresistance improving effect by the ultraviolet absorber is expressed asR_(YI)=(1−ΔYI₁/ΔYI₀)×100 (%), R_(YI)≦50% holds. The effect of theultraviolet absorber in the composition of the present invention issignificant, and the composition of the polycarbonate copolymer showsgood light resistance.

Molded articles produced by these methods are used for variousapplications requiring heat resistance, such as gradings, automobilelamp lenses, lamp covers, optical lenses, prisms, OHP sheets, nameplates, indicating lamps, light guides, optical waveguides anddiffusers. Further, films produced by these methods are suitably used asplacer boards intended for flat panel display boards or retardationfilms. When the film is used as the placer board, it is used in anunstretched condition. When the film is used as the retardation film, itis stretched and oriented at least monoaxially to have optimumbirefringence properties.

EXAMPLES

Hereinafter, the present invention will be further described withreference to Examples. However, the present invention is by no meanslimited to the Examples. In the Examples, “parts” refers to “parts byweight”. Evaluations were made in accordance with the following methods.

Evaluation Items

(1) Content of Fluorene-9-one in Polymer:

50 mg of sample was dissolved in 5 ml of chloroform solvent, and thecontent of fluorene-9-one in polymer was determined in the chloroformsolvent by a GPC analysis at a wavelength of 254 nm by use of TSK-GELG2000H and G3000H columns of Tosoh Corporation. More specifically, a GPCmeasurement was made on the sample to which a predetermined amount offluorene-9-one had been added in advance, a correlation equation for thepeak area proportion and the content was prepared, and the equation wasdefined as a calibration curve. The correlation equation is representedby the following equation.Fluorene-9-one content (ppm)=Peak Area Proportion (%)×302.7(2) Content of Fluorene-9-one in Monomer:

10 mg of sample was dissolved in 10 ml of acetonitrile, and the contentof fluorene-9-one in monomer was determined in a solvent ofacetonitrile/water in a ratio of 6/4 by an HPLC analysis at a wavelengthof 254 nm by use of TSK-GEL ODS-80 TM column of Tosoh Corporation.

(3) Intrinsic Viscosity:

A polymer was dissolved in methylene chloride, and intrinsic viscositywas measured at 20° C.

(4) b Value of Film:

A 200-μm-thick film obtained by casting a polymer solution on a glassplate was measured by use of U-3000 spectrophotometer of Hitachi, Ltd.in accordance with a transmission method.

(5) Specific Viscosity:

0.7 g of polymer was dissolved in 100 ml of methylene chloride, andspecific viscosity was measured at 20° C.

(6) Glass Transition Point (Tg):

This was measured by use of 2910 DSC of TA Instruments Japan Co., Ltd.under a nitrogen current of 40 ml/min at a temperature increasing rateof 20° C./min.

(7) Color of Sample Plate:

The yellowness (YI) of molded sample plate having a thickness of 2 mmwas measured by use of spectrocolorimeter SE-2000 (light source: C/2) ofNippon Denshoku Industries Co., Ltd. in accordance with a transmissionmethod.

(8) Light Resistance:

Without changing the irradiated surface of a molded sample plate havinga thickness of 2 mm, the sample plate was irradiated with ultravioletradiation by using a 400-W transparent mercury lamp of 300 to 400 nmwith an ultraviolet irradiation intensity of 15 mW/cm² as a light sourceat a test temperature of 80° C. for 7 days. The test sample wasrecovered, and a change in yellowness (YI) between before and after thetest was evaluated by use of spectrocolorimeter SE-2000 (light source:C/2) of Nippon Denshoku Industries Co., Ltd. in accordance with atransmission method.

The result of the test using a sample plate molded from an aromaticpolycarbonate resin containing no ultraviolet absorber was ΔYI₀, theresult of the test using a sample plate molded from an aromaticpolycarbonate resin composition containing a specified amount of anultraviolet absorber was ΔYI₁, and the degree (R_(YI)) of lightresistance improving effect was expressed as R_(YI)=(1−ΔYI₁/ΔYI₀)×100(%).

(9) Sulfur Content:

A full elementary analysis was made by use of an X-ray fluorescentanalyzer of Rigaku Corporation. The sulfur content was determined interms of the X-ray intensity of a sulfur atom.

(10) Viscosity Average Molecular Weight (Mv):

0.7 g of polycarbonate resin was dissolved in 100 ml of methylenechloride, and specific viscosity (η_(sp)) was measured at 20° C. Thespecific viscosity was substituted into the following equation so as todetermine the viscosity average molecular weight in terms of theintrinsic viscosity of polycarbonate resin obtained from bisphenol A.η_(sp) /c=[η]+0.45×[η]² c[η]=1.23×10⁻⁴ M ^(0.83)(wherein [η] is intrinsic viscosity, and c=0.7)(11) b Value of Molded Piece:

20 molded pieces were measured by use of colorimeter SE-2000 (lightsource: C/2) of Nippon Denshoku Industries Co., Ltd. in accordance witha transmission method. The average of the measured values of the 20pieces was taken as the b value of the molded piece.

(12) Odor:

An odor was evaluated in accordance with a sensory test. Those fromwhich a sulfur odor was sensed during an extrusion or molding processwas rated as “Yes”, and those from which a sulfur odor was not sensedwas rated as “No”.

(13) Residual Quantity of Hydrosulfite:

An ultraviolet spectrum was measured by use of a spectrophotometer ofHitachi, Ltd., and the residual quantity of hydrosulfite was determinedin terms of absorbance at 315 nm.

(14) Monomer Purity:

An HPLC analysis was conducted in accordance with a gradient program at40° C. and 280 nm by use of eluent acetonitrile/a mixed solution of 0.2%acetate water and acetonitrile in a Develosil ODS-MG column of NomuraChemical Co., Ltd. The measurement was made by injecting 10 μl ofsolution prepared by dissolving 3 mg of sample in 10 ml of acetonitrile,and the proportion of the peak area of the main component based on thetotal peak area was expressed in %.

(15) Analysis of Trace Chlorine Content:

About 0.5 g of polymer was precisely weighed, methylene chloride wasadded to dissolve the polymer, and 1 ml of 0.5 g/l methylene chloridesolution of 4-(p-nitrobenzyl)pyridine (product of Wako Pure ChemicalIndustries, Ltd., special grade chemical) was added thereto to adjustthe total amount of the mixture to 10 ml. Absorbance was measured at awavelength of 440 nm by use of a spectrophotometer (U-3000 of Hitachi,Ltd.).

Separately, a calibration curve was prepared by use of a methylenechloride solution of phenyl chlorocarbonate (product of Wako PureChemical Industries, Ltd., special grade chemical), and a trace chlorinecontent derived from chloroformate groups in the sample was determined.The determination limit was a solid content of 0.2 ppm in terms ofchlorine content.

(16) Terminal Hydroxyl Group Content:

After about 0.2 g of polymer was charged into a 25-ml measuring flaskand precisely weighed, about 10 ml of methylene chloride was added todissolve the polymer. After the polymer was dissolved, 10 ml of titaniumtetrachloride solution and 4 ml of acetic acid solution were added, andmethylene chloride was added to make the mixture reach the marked line.The titanium tetrachloride solution was prepared by charging 20 g oftitanium tetrachloride and 0.2 g of acetic acid into a 500-ml measuringflask and adding methylene chloride to make the mixture reach the markedline. The acetic acid solution was prepared by charging 10 g of aceticacid into a 100-ml measuring flask and adding methylene chloride to makethe mixture reach the marked line. After the sample solution was shakenwell, absorbance at 500 nm was measured by use of water as a blank, andthe hydroxyl group content was determined.

(17) Total Light Transmittance:

This was measured by use of MDH-300A of Nippon Denshoku Industries Co.,Ltd. in accordance with ASTM D-1003.

(18) Cloudiness in Aluminum Evaporation:

An aluminum film having a thickness of 100 nm was evaporated on a sampleplate having a size of 50 mm×90 mm×2 mm by a vacuum evaporationapparatus of DIAVAC LIMITED, and a change in the aluminum film after thefilm was left to stand in an atmosphere of 160° C. for 24 hours wasobserved. When cloudiness was found in the aluminum evaporated film, itwas rated as “x”, and when no change was found in the aluminumevaporated film, it was rated as “◯”.

(19) Reflow Resistance:

An test piece prepared by injection molding and having a thickness of1.0 mm, a width of 10 mm and a length of 20 mm was dried under reducedpressure at 120° C. for 10 hours. This test piece was treated in areflow furnace (TPF-20L of Asahi Engineering Co., Ltd.) using infraredradiation and hot air in combination. The heating temperature patternwas set so that a peak temperature of 250° C. lasted for 5 seconds afterheating at 150° C. for 60 seconds, and a change in the color of thereflow-treated molded piece was visually evaluated. Those showing nochange in color were rated as “◯”, and those showing a change in colorwere rated as “x”n.

(20) b Value of Monomer Solution:

10 g of sample was dissolved in 50 ml of ethanol, and the b value of thesolution was measured in a sample tube having an optical path length of30 mm by use of colorimeter 300A of Nippon Denshoku Industries Co., Ltd.

(21) Average Brightness (1):

A test piece having a length of 231 mm, a width of 321 mm and athickness of 1 to 2 mm was installed in a 15-type direct-backlight unit.Brightness (cd/m²) at 9 points on the test piece was measured bybrightness photometer BM-7 of TOPCON CORPORATION, and the averagethereof was taken as average brightness.

(22) Brightness Non-Uniformity:

The ratio of the minimum brightness to the maximum brightness out of theabove results of measurements of brightness was taken as brightnessnon-uniformity.brightness non-uniformity (%)=(minimum brightness/maximumbrightness)×100(23) Light Diffusibility:

Test pieces through which a cold cathode as a light source was not seenwhen installed in the above backlight unit were rated as “◯”, and testpieces through which a cold cathode as a light source was seen wheninstalled in the above backlight unit were rated as “x”.

(24) Change in Brightness Non-Uniformity:

Test pieces showing no change in brightness non-uniformity when used ina high temperature atmosphere of 140° C. were rated as “◯”, and testpieces showing a change in brightness non-uniformity when used in a hightemperature atmosphere of 140° C. were rated as “x”.

(25) Heat Resistance:

Test pieces which did not undergo deformation even when left to stand inan atmosphere of 160° C. for 24 hours were rated as “◯”, and test pieceswhich underwent deformation when left to stand in an atmosphere of 160°C. for 24 hours were rated as “x”.

(26) Average Brightness (2):

An optical waveguide test piece having a length of 100 mm, a width of100 mm and a thickness of 1 to 2 mm was installed in a backlight unit,irradiated with a cold cathode from the edge, brightness (cd/m²) at 9points on the test piece was measured by brightness photometer BM-7 ofTOPCON CORPORATION, and the average thereof was taken as averagebrightness.

(27) Refractive Index:

This was measured by use of Abbe's refractometer.

Example 1

To a reactor equipped with a thermometer, agitator and reflux condenser,190,500 parts of ion exchanged water and 105,400 parts of 25% sodiumhydroxide solution were added. After 20 minutes after 43,560 parts of9,9-bis(4-hydroxy-3-methylphenyl)fluorene (hereinafter may beabbreviated as “BCF” or “biscresol fluorene”) having a fluorene-9-onecontent measured by the above HPLC analysis of 2.1 ppm, 11,260 parts of2,2-bis(4-hydroxyphenyl)propane (hereinafter may be abbreviated as “BPA”or “bisphenol A”) and 110 parts of hydrosulfite were dissolved, 178,400parts of methylene chloride was added. Thereafter, under agitation,22,810 parts of phosgene was blown into the mixture at 15 to 25° C. for60 minutes. After completion of phosgene blowing, a solution prepared bydissolving 222.2 parts of p-t-butylphenol in 3,300 parts of methylenechloride and 13,200 parts of 25% sodium hydroxide solution were added.After emulsification, 40 parts of triethylamine was added, and theresulting mixture was stirred at 28 to 33° C. for 1 hour so as tocomplete the reaction. After completion of the reaction, the product wasdiluted with methylene chloride, rinsed with water, rendered acidic withhydrochloric acid and rinsed with water, and when the electricconductivity of the water phase became nearly the same as that of ionexchanged water, the methylene chloride phase was concentrated anddehydrated to obtain a solution having a polycarbonate concentration of20%. A polycarbonate obtained by removing the solvent from this solutionshowed a molar ratio between biscresol fluorene and bisphenol Aconstituents of 70:30 (polymer yield: 97%). Further, this polymer had anintrinsic viscosity of 0.675 and a Tg of 227° C. The content offluorene-9-one in the obtained polymer was 2.3 ppm. This polycarbonatesolution was cast on a moving stainless steel plate from a T die at 20°C., the temperature was gradually increased to evaporate methylenechloride, and the formed film was removed from the stainless steel plateand further heated to remove methylene chloride. Thereby, a film havinga thickness of 200 μm was obtained. Casting film formability was good,and this film had a b value of 0.6.

Example 2

A polymer 20% solution showing a molar ratio between biscresol fluoreneand bisphenol A constituents of 60:40 was obtained (polymer yield: 98%)in the same manner as in Example 1 except that the amount of biscresolfluorene was 37,200 parts and the amount of bisphenol A was 15,000parts. This polymer had an intrinsic viscosity of 0.709 and a Tg of 218°C. The content of fluorene-9-one in the obtained polymer was 2.1 ppm. Afilm having a thickness of 200 μm was obtained from this polycarbonatesolution in the same manner as in Example 1. Casting film formabilitywas good, and this film had a b value of 0.5.

Example 3

A polymer 20% solution showing a molar ratio between biscresol fluoreneand α,α′-bis(4-hydroxyphenyl)-m-diisopropylbenzene (hereinafter may beabbreviated as “BPM” or “bisphenol M”) constituents of 70:30 wasobtained (polymer yield: 97%) in the same manner as in Example 1 exceptthat 17,089 parts by weight of bisphenol M was used in place ofbisphenol A. This polymer had an intrinsic viscosity of 0.671 and a Tgof 209° C. The content of fluorene-9-one in the obtained polymer was 2.4ppm. A film having a thickness of 200 μm was obtained from thispolycarbonate solution in the same manner as in Example 1. Casting filmformability was good, and this film had a b value of 0.6.

Example 4

To a reactor equipped with a thermometer, agitator and reflux condenser,190,500 parts of ion exchanged water and 105,400 parts of 25% sodiumhydroxide solution were added. After 43,560 parts of9,9-bis(4-hydroxy-3-methylphenyl)fluorene having a fluorene-9-onecontent measured by the above HPLC analysis of 17 ppm, 11,260 parts of2,2-bis(4-hydroxyphenyl)propane and 110 parts of hydrosulfite weredissolved, 178,400 parts of methylene chloride was added immediately.Thereafter, under agitation, 22,810 parts of phosgene was blown into themixture at 15 to 25° C. for 60 minutes. After completion of phosgeneblowing, a solution prepared by dissolving 222.2 parts ofp-t-butylphenol in 3,300 parts of methylene chloride and 13,200 parts of25% sodium hydroxide solution were added. After emulsification, 40 partsof triethylamine was added, and the resulting mixture was stirred at 28to 33° C. for 1 hour so as to complete the reaction. After completion ofthe reaction, the product was diluted with methylene chloride, rinsedwith water, rendered acidic with hydrochloric acid and rinsed withwater, and when the electric conductivity of the water phase becamenearly the same as that of ion exchanged water, the methylene chloridephase was concentrated and dehydrated to obtain a solution having apolycarbonate concentration of 20%. A polycarbonate obtained by removingthe solvent from this solution showed a molar ratio between biscresolfluorene and bisphenol A constituents of 70:30 (polymer yield: 97%).Further, this polymer had an intrinsic viscosity of 0.674 and a Tg of226° C. The content of fluorene-9-one in the obtained polymer was 13ppm. A film having a thickness of 200 μm was obtained from thispolycarbonate solution in the same manner as in Example 1. This film hada b value of 0.9.

Example 5

A 20% polycarbonate solution (polymer yield: 95%) was obtained in thesame manner as in Example 1 except that the reaction was carried outwhile nitrogen was blown into the reaction. This polymer had anintrinsic viscosity of 0.672 and a Tg of 225° C. Further, the content offluorene-9-one in the obtained polymer was 1.5 ppm. A film having athickness of 200 μm was obtained from this polycarbonate solution in thesame manner as in Example 1. This film had a b value of 0.3.

Comparative Example 1

A 20% polycarbonate solution (polymer yield: 94%) was obtained in thesame manner as in Example 1 except that methylene chloride was addedafter passage of at least 2.5 hours after biscresol fluorene, bisphenolA and hydrosulfite were dissolved. This polymer had an intrinsicviscosity of 0.669 and a Tg of 223° C. Further, the content offluorene-9-one in the obtained polymer was 34 ppm. A film having athickness of 200 μm was obtained from this polycarbonate solution in thesame manner as in Example 1. This film had a b value of 1.6.

Comparative Example 2

A 20% polycarbonate solution (polymer yield: 95%) was obtained in thesame manner as in Example 3 except that methylene chloride was addedafter passage of at least 2.5 hours after biscresol fluorene, bisphenolM and hydrosulfite were dissolved. This polymer had an intrinsicviscosity of 0.668 and a Tg of 209° C. Further, the content offluorene-9-one in the obtained polymer was 41 ppm. A film having athickness of 200 μm was obtained from this polycarbonate solution in thesame manner as in Example 3. This film had a b value of 1.9.

Comparative Example 3

A 20% polycarbonate solution (polymer yield: 97%) was obtained in thesame manner as in Example 4 except that the time spanning fromdissolving an aromatic dihydroxy compound in an acid binding agent and asolvent completely to the start of its reaction with a carbonateprecursor was 30 minutes. This polymer had an intrinsic viscosity of0.673 and a Tg of 225° C. Further, the content of fluorene-9-one in theobtained polymer was 31 ppm. A film having a thickness of 200 μm wasobtained from this polycarbonate solution in the same manner as inExample 4. This film had a b value of 1.6.

Comparative Example 4

A 20% polycarbonate solution (polymer yield: 95%) was obtained by use ofthe same reactor as used in Example 1 in the same manner as in Example 1except that biscresol fluorene having a fluorene-9-one content of 35 ppmwas used. This polymer had an intrinsic viscosity of 0.674 and a Tg of226° C. Further, the content of fluorene-9-one in the obtained polymerwas 67 ppm. A film having a thickness of 200 μm was obtained from thispolycarbonate solution in the same manner as in Example 1. This film hada b value of 2.2. TABLE 1 Fluorene-9-one Fluorene-9-one Content of BCFBPA BPM Tg η Content of BCF Copolymer B Value mol % mol % mol % ° C. —ppm ppm of Film Ex. 1 70 30 0 227 0.675 2.1 2.3 0.6 Ex. 2 60 40 0 2180.709 2.1 2.1 0.5 Ex. 3 70 0 30 209 0.671 2.1 2.4 0.6 Ex. 4 70 30 0 2260.674 17.0 13.0 0.9 Ex. 5 70 30 0 225 0.672 2.1 1.5 0.3 C. Ex. 1 70 30 0223 0.669 2.1 34.0 1.6 C. Ex. 2 70 0 30 209 0.668 2.1 41.0 1.9 C. Ex. 370 30 0 225 0.673 17.0 31.0 1.6 C. Ex. 4 70 30 0 226 0.674 35.0 67.0 2.2Ex.: Example,C. Ex.: Comparative Example

Examples 6 to 9 and Comparative Examples 5 to 9

Polycarbonate copolymers (a) and ultraviolet absorbers (b) used in theseExamples and Comparative Examples are as follows.

(a) Polycarbonate Copolymer (PC Resin)

⊚ Production of Polycarbonate Copolymer—Case 1

To a reactor equipped with a thermometer, agitator and reflux condenser,19,580 parts of ion exchanged water and 3,845 parts of 48% sodiumhydroxide solution were added. After 20 minutes after 2,835 parts ofbisphenol A, 1,175 parts of biscresol fluorene having a fluorene-9-onecontent measured by the above HPLC analysis of 2.1 ppm and 8.4 parts ofhydrosulfite were dissolved, 13,209 parts of methylene chloride wasadded. Then, under agitation, 2,000 parts of phosgene was blown into themixture at 18 to 20° C. for 60 minutes. After completion of phosgeneblowing, 93.2 parts of p-t-butylphenol and 641 parts of 48% sodiumhydroxide solution were added. Then, 2.0 parts of triethylamine wasadded, and the resulting mixture was stirred at 20 to 27° C. for 40minutes to complete the reaction. After completion of the reaction, theproduct was diluted with methylene chloride, rinsed with water, renderedacidic with hydrochloric acid and rinsed with water, and when theelectric conductivity of the water phase became nearly the same as thatof ion exchanged water, methylene chloride was evaporated by a kneaderto obtain 4,250 parts of pale yellow polymer (abbreviated as “EX-PC1”)having a molar ratio of bisphenol A to biscresol fluorene of 80:20, aspecific viscosity of 0.370 and a Tg of 172° C. (yield: 95%). Thecontent of fluorene-9-one in the obtained polymer was 1.5 ppm.

⊚ Production of Polycarbonate Copolymer—Case 2

To a reactor equipped with a thermometer, agitator and reflux condenser,21,540 parts of ion exchanged water and 4,230 parts of 48% sodiumhydroxide solution were added. After 20 minutes after 1,949 parts ofbisphenol A, 3,231 parts of biscresol fluorene having a fluorene-9-onecontent measured by the above HPLC analysis of 2.1 ppm and 10.9 parts ofhydrosulfite were dissolved, 14,530 parts of methylene chloride wasadded. Then, under agitation, 2,200 parts of phosgene was blown into themixture at 16 to 20° C. for 60 minutes. After completion of phosgeneblowing, 115.4 parts of p-t-butylphenol and 705 parts of 48% sodiumhydroxide solution were added. Then, 2.6 parts of triethylamine wasadded, and the resulting mixture was stirred at 20 to 27° C. for 40minutes to complete the reaction. After completion of the reaction, theproduct was diluted with methylene chloride, rinsed with water, renderedacidic with hydrochloric acid and rinsed with water, and when theelectric conductivity of the water phase became nearly the same as thatof ion exchanged water, methylene chloride was evaporated by a kneaderto obtain 5,500 parts of pale yellow polymer (abbreviated as “EX-PC2”)having a molar ratio of bisphenol A to biscresol fluorene of 50:50, aspecific viscosity of 0.280 and a Tg of 198° C. (yield: 95%). Thecontent of fluorene-9-one in the obtained polymer was 2.0 ppm.

Production of Comparative Aromatic Polycarbonate Resin

To a reactor equipped with a thermometer, agitator and reflux condenser,19,760 parts of ion exchanged water and 4,240 parts of 48% sodiumhydroxide solution were added. After 5,010 parts of bisphenol A and 10.0parts of hydrosulfite were dissolved and 12,510 parts of methylenechloride was added, 2,500 parts of phosgene was blown into the mixtureunder agitation at 18 to 20° C. over 60 minutes. After completion ofphosgene blowing, 148.2 parts of p-t-butylphenol and 650 parts of 48%sodium hydroxide solution were added. Then, 5.5 parts of triethylaminewas added, and the resulting mixture was stirred at 20 to 27° C. for 40minutes to complete the reaction. After completion of the reaction, theproduct was diluted with methylene chloride, rinsed with water, renderedacidic with hydrochloric acid and rinsed with water, and when theelectric conductivity of the water phase became nearly the same as thatof ion exchanged water, methylene chloride was evaporated by a kneaderto obtain 5,380 parts of white bisphenol A homopolymer (abbreviated as“CEX-PC1”) having a specific viscosity of 0.368 and a Tg of 145° C.(yield: 94%).

(b) Ultraviolet Absorber (UVA)

-   ⊚ 2,2′-p-phenylenebis(3,1-benzoxazine-4-one): CEi-P of Takemoto oil    & fat. (abbreviated as “EX-UVA1”)-   ⊚ 2,2′-(4,4′-diphenylene)bis(3,1-benzoxazine-4-one): synthesized and    used (abbreviated as “EX-UVA2”)-   ⊚ 1,4-bis(4-benzoyl-3-hydroxyphenoxy)butane: SHEESORB 151 of SHIPRO    CO., LTD. (abbreviated as “CEX-UVA1”)-   ⊚ 2-[5-chloro(2H)-benzotriazole-2-yl]-4-methyl-6-(t-butyl) phenol:    CINUBIN 326 of Ciba Specialty Chemicals K.K. (abbreviated as    “CEX-UVA2”)

Table 2 shows the absorbance at 360 nm (A_(360 nm)) and absorbance at400 nm (A_(400 nm)) measured at an optical path length of 1 cm whendissolved in methylene chloride at a concentration of 10 mg/L of theultraviolet absorbers, the glass transition temperatures (Tg) of EX-PC1and EX-PC2 containing no ultraviolet absorber, and the glass transitiontemperatures (Tg′) of aromatic polycarbonate resin compositions preparedby adding 2 parts by weight of the ultraviolet absorbers to 100 parts byweight of EX-PC1 and EX-PC2. TABLE 2 Type of PC Type of UltravioletA_(360 nm) A_(400 nm) Tg Tg′ Resins Absorber — — ° C. ° C. EX-PC1EX-UVA1 0.645 0.001 172 169 EX-PC2 198 196 EX-PC1 CEX-UVA2 0.670 0.005172 170 EX-PC2 198 197 EX-PC1 CEX-UVA1 0.099 0.001 172 166 EX-PC2 198190 EX-PC1 CEX-UVA2 0.481 0.037 172 167 EX-PC2 198 193Preparation of Polycarbonate Composition

To EX-PC1 and EX-PC2 obtained above, 0.0050% of5,7-di-t-butyl-3-(3,4-dimethylphenyl)-3H-benzofurano-2-one, 0.050% ofbis(2,4-dicumylphenyl)pentaerythritol diphosphite and 0.050% ofpentaerythritol tetrastearate were added. Further, the ultravioletabsorbers shown in Table 3 were uniformly mixed into the mixtures by useof a tumbler. Then, the resulting mixtures were pelletized by a 30-mm-φvented twin screw extruder (KTX-30 of Kobe Steel, Ltd.) at a cylindertemperature of 300° C. and a vacuum degree of 10 mmHg under deaeration.After the obtained pellets were dried at 120° C. for 5 hours, testsample plates having a thickness of 2 mm were prepared by use of aninjection molding machine (SG150U of Sumitomo Heavy Industries, Ltd.) ata cylinder temperature of 320° C. and a mold temperature of 100° C. Theresults of evaluations are shown in Table 3.

As is clear from comparisons among the obtained test sample plates, itis understood that aromatic polycarbonate resin compositions comprisingthe polycarbonate copolymers of the present invention and the specificultraviolet absorbers have excellent light resistance. TABLE 3 PC AmountItem Resin UVA of UVA Tg YI ΔYI₀ ΔYI₁ R_(YI) Unit — — wt % ° C. — — — —Ex. 6 EX-PC1 EX- 0.3 171 1.2 16.5 4.2 75 UVA1 Ex. 7 EX-PC1 EX- 1.0 1681.8 16.5 3.1 81 UVA1 Ex. 8 EX-PC2 EX- 1.0 194 5.7 23.5 7.2 69 UVA1 Ex. 9EX-PC1 EX- 1.0 171 2.2 16.5 3.8 77 UVA2 C. Ex. 5 EX-PC1 — — 172 1.1 16.516.5 0 C. Ex. 6 EX-PC2 — — 198 5.5 23.5 23.5 0 C. Ex. 7 EX-PC1 CEX- 0.3170 1.1 16.5 12.4 25 UVA1 C. Ex. 8 EX-PC1 CEX- 0.3 169 12.2 16.5 6.7 59C. Ex. 9 CEX- EX- 0.3 144 0.8 3.5 2.5 29 PC1 UVA1

Example 10

To a reactor equipped with a thermometer, agitator and reflux condenser,22,109 parts of ion exchanged water and 3,925 parts of 48% sodiumhydroxide solution were added. After 20 minutes after 1,162 parts of9,9-bis (4-hydroxy-3-methylphenyl) fluorene (hereinafter may beabbreviated as “biscresol fluorene”) having a fluorene-9-one contentmeasured by the above HPLC analysis of 2.1 ppm, 2,804 parts of2,2-bis(4-hydroxyphenyl)propane (hereinafter may be abbreviated as“bisphenol A”) and 130 parts of hydrosulfite were dissolved, 15,661parts of methylene chloride was added. Then, 1,900 parts of phosgene wasblown into the mixture under agitation at 15 to 25° C. for 60 minutes.After completion of phosgene blowing, a solution prepared by dissolving92 parts of p-t-butylphenol in 330 parts of methylene chloride and 633parts of 48% sodium hydroxide solution were added. After emulsification,5 parts of triethylamine was added, and the resulting mixture wasstirred at 28 to 33° C. for 1 hour so as to complete the reaction. Aftercompletion of the reaction, the product was diluted with methylenechloride and then rinsed with water repeatedly until the content ofhydrosulfite remaining in the water phase became 5 ppm or less. Then,the resulting product was rendered acidic with hydrochloric acid andrinsed with water again until it became neutral. After dehydration,methylene chloride was removed so as to obtain a polymer having a molarratio between biscresol fluorene and bisphenol A constituents of 20:80(polymer yield: 97%). This polymer had a glass transition temperature(Tg) of 165° C. and a viscosity average molecular weight (Mv) of 18,500.The content of fluorene-9-one in the obtained polymer was 1.5 ppm. Thecontent of sulfur in this polymer was 12 ppm in terms of sulfur atom.Then, 0.1 wt % of “Irgafos 168” of Ciba Specialty Chemicals was added tothis polymer, and the mixture was extruded by use of a 30-φ single screwextruder at a cylinder temperature of 300° C. so as to pelletize it.After the pellets were plasticized by use of an injection moldingmachine (Nikko Anchor V-17-65 of Japan Steel Works, Ltd.) at a cylindertemperature of 340° C., a test piece having a thickness of 2 mm wasobtained. At that time, a sulfur odor was not sensed. Further, the bvalue of the test piece was good at 1.4. The results are shown in Table4.

Example 11

To the same reactor as used in Example 10, 23,272 parts of ion exchangedwater and 3,999 parts of 48% sodium hydroxide were added. After 20minutes after 1,845 parts of bisphenol A, 3,058 parts of biscresolfluorene having a fluorene-9-one content measured by the above HPLCanalysis of 2.1 ppm and 140 parts of hydrosulfite were dissolved, 16,485parts of methylene chloride was added. Then, 1,920 parts of phosgene wasblown into the mixture under agitation at 15 to 20° C. for 60 minutes.After completion of phosgene blowing, 97 parts of p-t-butylphenol and666 parts of 48% sodium hydroxide solution were added. Afteremulsification, 5.6 parts of triethylamine was added, and the resultingmixture was stirred at 28 to 33° C. for 1 hour so as to complete thereaction. The product was treated in the same manner as in Example 10 soas to obtain a polymer having a molar ratio between biscresol fluoreneand bisphenol A of 50:50 (yield: 96%). This polymer had a glasstransition temperature (Tg) of 197° C. and a viscosity average molecularweight (Mv) of 15,500. The content of fluorene-9-one in the obtainedpolymer was 2.1 ppm. The content of sulfur in this polymer was 11 ppm interms of sulfur atom. Then, 0.1 wt % of “Irgafos 168” of Ciba SpecialtyChemicals was added to this polymer, and the mixture was extruded by useof a 30-φ single screw extruder at a cylinder temperature of 300° C. soas to pelletize it. After the pellets were plasticized by use of aninjection molding machine (Nikko Anchor V-17-65 of Japan Steel Works,Ltd.) at a cylinder temperature of 340° C., a test piece having athickness of 2 mm was obtained. At that time, a sulfur odor was notsensed. Further, the b value of the test piece was good at 1.5. Theresults are shown in Table 4.

Example 12

To the same reactor as used in Example 10, 35,315 parts of ion exchangedwater and 3,920 parts of 48% sodium hydroxide were added. After 20minutes after 2,954.9 parts ofα,α′-bis(4-hydroxyphenyl)-m-diisopropylbenzene (abbreviated as“bisphenol M”), 3,228.1 parts of biscresol fluorene having afluorene-9-one content measured by the above HPLC analysis of 2.1 ppmand 150 parts of hydrosulfite were dissolved, 12,775 parts of methylenechloride was added. Then, 1,946 parts of phosgene was blown into themixture under agitation at 15 to 20° C. for 60 minutes. After completionof phosgene blowing, 108.5 parts of p-t-butylphenol and 710.5 parts of48% sodium hydroxide solution were added. After emulsification, 4.55parts of triethylamine was added, and the resulting mixture was stirredat 28 to 33° C. for 1 hour so as to complete the reaction. The productwas treated in the same manner as in Example 10 so as to obtain apolymer having a molar ratio between bisphenol M and biscresol fluoreneconstituents of 50:50 (yield: 98%). This polymer had a glass transitiontemperature (Tg) of 180° C. and a viscosity average molecular weight(Mv) of 13,200. The content of fluorene-9-one in the obtained polymerwas 2.1 ppm. The content of sulfur in this polymer was 15 ppm in termsof sulfur atom. Then, 0.1 wt % of “Irgafos 168” of Ciba SpecialtyChemicals was added to this polymer, and the mixture was extruded by useof a 30-φ single screw extruder at a cylinder temperature of 300° C. soas to pelletize it. After the pellets were plasticized by use of aninjection molding machine (Nikko Anchor V-17-65 of Japan Steel Works,Ltd.) at a cylinder temperature of 340° C., a test piece having athickness of 2 mm was obtained. At that time, a sulfur odor was notsensed. Further, the b value of the test piece was good at 1.6. Theresults are shown in Table 4. TABLE 4 Tg Sulfur Content (° C.) (ppm) bValue Odor Example 10 165 12 1.4 None Example 11 197 11 1.5 None Example12 180 15 1.6 None

Example 13

To a reactor equipped with a thermometer, agitator and reflux condenser,19,580 parts of ion exchanged water and 4,486 parts of 48% sodiumhydroxide solution were added. After 20 minutes after 2,349.7 parts of9,9-bis(4-hydroxy-3-methylphenyl)fluorene having a fluorene-9-onecontent measured by the above HPLC analysis of 2.1 ppm and a purity of99.9%, 2,125.9 parts of 2,2-bis(4-hydroxyphenyl)propane and 13 parts ofhydrosulfite were dissolved, 13,210 parts of methylene chloride wasadded. Then, 2,000 parts of phosgene was blown into the mixture underagitation at 15 to 25° C. for 60 minutes. After completion of phosgeneblowing, a solution prepared by dissolving 104.9 parts ofp-t-butylphenol in 500 parts of methylene chloride and 640.8 parts of48% sodium hydroxide solution were added. After emulsification, 7.4parts of triethylamine was added, and the resulting mixture was stirredat 28 to 33° C. for 1 hour so as to complete the reaction. Aftercompletion of the reaction, the product was diluted with methylenechloride, rinsed with water, rendered acidic with hydrochloric acid andrinsed with water, and when the electric conductivity of the water phasebecame nearly the same as that of ion exchanged water, the methylenechloride phase was concentrated and dehydrated to obtain a solutionhaving a polycarbonate concentration of 20%. A polycarbonate obtained byremoving the solvent from this solution showed a molar ratio betweenbiscresol fluorene and bisphenol A constituents of 40:60 (polymer yield:97%). Further, this polymer had an intrinsic viscosity of 0.312 and a Tgof 189° C. The content of fluorene-9-one in the obtained polymer was 2.0ppm. Further, the content of trace chlorine based on chloroformategroups in the polymer was 0.3 ppm, and the content of hydroxyl groupswas 70.7 ppm. To 100 parts of this polymer, 0.05 parts oftetrakis(2,4-di-t-butylphenyl)-4,4-diphenylene phosphonite, 0.01 partsof octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate and 0.05 partsof monoglyceride stearate were added, and the resulting mixture wasmelt-extruded from a vented extruder at an extruder temperature of 280to 320° C. and a die temperature of 290 to 330° C. with the degree ofvacuum of the vent kept at 2.7 kPa so as to pelletize it. After thepellets were. dried at 120° C. for 4 hours, they were injection-moldedinto a test piece having a size of 50 mm×90 mm×2 mm. The obtained moldedpiece had a total light transmittance of 89% and a b value of 1.4. Whenthe molded piece was subjected to aluminum evaporation and a heattreatment and the surface condition thereof was visually evaluated, nocloudiness was observed. Further, no change was observed with respect tothe color of the molded piece after a reflow treatment. The results areshown in Table 5.

Example 14

A polymer having a molar ratio between biscresol fluorene and bisphenolA of 70:30 was obtained in the same manner as in Example 13 except thatthe amount of biscresol fluorene was 4,111.9 parts and the amount ofbisphenol A was 1,062.9 parts. This polymer had a specific viscosity of0.262 and a Tg of 215° C. The content of fluorene-9-one in the obtainedpolymer was 2.3 ppm. This polymer was pelletized in the same manner asin Example 13. The results of evaluations made on the obtained moldedpiece are shown in Table 5.

Example 15

A polymer having a molar ratio between biscresol fluorene and bisphenolA of 40:60 was obtained in the same manner as in Example 13 except thatbiscresol fluorene having a fluorene-9-one content measured by the aboveHPLC analysis of 2.1 ppm and a purity of 99.2% was used. This polymerhad a specific viscosity of 0.296 and a Tg of 189° C. The content offluorene-9-one in the obtained polymer was 2.0 ppm. This polymer waspelletized in the same manner as in Example 13. The results ofevaluations made on the obtained molded piece are shown in Table 5.TABLE 5 Composition Content of Chlorine Purity of Polymer Based on ofBCF (%) Specific Tg Chloroformate (%) BCF BPA Viscosity (° C.) Group(ppm) Ex. 13 99.9 40 60 0.312 189 0.3 Ex. 14 99.9 70 30 0.262 215 0.6Ex. 15 99.2 40 60 0.296 189 5.0 Content of Cloudiness Hydroxyl TotalLight b Value of in Reflow Group Transmittance Molded Aluminum Resis-(ppm) (%) Piece Evaporation tance Ex. 13 70.7 89 1.4 ◯ ◯ Ex. 14 57.7 892.3 ◯ ◯ Ex. 15 103.2 89 1.6 ◯ ◯Ex.: Example

Examples 16 to 20 Synthesis Example 1

To a reactor equipped with a thermometer, agitator and reflux condenser,24,623 parts of ion exchanged water and 4,153 parts of 48% sodiumhydroxide solution were added. After 20 minutes after 1,936.9 parts of9,9-bis(4-hydroxy-3-methylphenyl)fluorene having a fluorene-9-onecontent measured by the above HPLC analysis of 2.1 ppm, 2,726 parts of2,2-bis(4-hydroxyphenyl)propane and 8 parts of hydrosulfite weredissolved, 18,188 parts of methylene chloride was added. Thereafter,1,994 parts of the above phosgene was blown into the mixture underagitation at 15 to 25° C. for 60 minutes. After completion of phosgeneblowing, a solution prepared by dissolving 102.5 parts ofp-t-butylphenol in 330 parts of methylene chloride and 692.1 parts of48% sodium hydroxide solution were added. After emulsification, 5.8parts of triethylamine was added, and the resulting mixture was stirredat 28 to 33° C. for 1 hour so as to complete the reaction. Aftercompletion of the reaction, the product was diluted with methylenechloride, rinsed with water, rendered acidic with hydrochloric acid andrinsed with water, and when the electric conductivity of the water phasebecame nearly the same as that of ion exchanged water, the methylenechloride phase was concentrated and dehydrated to obtain a solutionhaving a polycarbonate concentration of 20%. A polycarbonate obtained byremoving the solvent from this solution showed a molar ratio betweenbiscresol fluorene and bisphenol A constituents of 30:70 (polymer yield:97%). Further, this polymer had an intrinsic viscosity of 0.337 and a Tgof 190° C. The content of fluorene-9-one in the obtained polymer was 1.9ppm. This polymer is referred to as polycarbonate A.

Synthesis Example 2

5,300 parts of polymer having a molar ratio between biscresol fluoreneand bisphenol A of 50:50 was obtained in the same manner as in SynthesisExample 1 except that the amount of biscresol fluorene was 3,171.4 partsand the amount of bisphenol A was 1,913 parts (yield: 96%). This polymerhad a specific viscosity of 0.320 and a Tg of 205° C. The content offluorene-9-one in the obtained polymer was 2.1 ppm. This polymer isreferred to as polycarbonate B.

Synthesis Example 3

To a reactor equipped with a thermometer, agitator and reflux condenser,35,315 parts of ion exchanged water and 3,920 parts of 48% sodiumhydroxide solution were added. After 20 minutes after 3,228.1 parts of9,9-bis(4-hydroxy-3-methylphenyl)fluorene having a fluorene-9-onecontent measured by the above HPLC analysis of 2.1 ppm, 2,954.9 parts ofα,α′-bis(4-hydroxyphenyl)-m-diisopropylbenzene and 14 parts ofhydrosulfite were dissolved, 12,775 parts of methylene chloride wasadded. Thereafter, 1,946 parts of the above phosgene was blown into themixture under agitation at 15 to 25° C. for 45 minutes. After completionof phosgene blowing, a solution prepared by dissolving 108.5 parts ofp-t-butylphenol in 330 parts of methylene chloride and 710.5 parts of48% sodium hydroxide solution were added. After emulsification, 4.55parts of triethylamine was added, and the resulting mixture was stirredat 28 to 33° C. for 1 hour so as to complete the reaction. The productwas treated in the same manner as in Synthesis Example 1 to obtain apolymer having a molar ratio between bisphenol M and biscresol fluoreneconstituents of 50:50 (yield: 98%). This polymer had a specificviscosity of 0.250 and a Tg of 180° C. The content of fluorene-9-one inthe obtained polymer was 2.1 ppm. This polymer is referred to aspolycarbonate C.

Examples 16 to 20

To the polycarbonate resins obtained in Synthesis Examples 1 to 3, 0.05parts of tris(2,4-di-t-butylphenyl)phosphite, 0.01 parts ofoctadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate and 0.03 parts ofpentaerythritol tetrastearate were added. Then, to the obtainedmixtures, transparent fine particles, a fluorescent brightening agent(KAYALIGHT OS of NIPPON KAYAKU KOGYO CO., LTD.) and2,2′-p-phenylenebis(3,1-benzoxazine-4-one) as an ultraviolet absorberwhose amounts were adjusted to those shown in Table 6 were added. Theresulting mixtures were melt-extruded into a light diffusing platehaving a width of 1,000 mm from a vented T-die extruder at an extrudertemperature of 280 to 320° C. and a die temperature of 290 to 330° C.with the degree of vacuum of the vent kept at 27 kPa. The results ofevaluations are shown in Table 6. TABLE 6 Ex. 16 Ex. 17 Ex. 18 Ex. 19Ex. 20 Thickness (mm) 2 2 2 2 1 PC (parts by weight) A 96.5 A 96.5 B96.5 C 96.5 A 96.5 Transparent Particles (parts by weight) i 3.5 ii 3.5i 3.5 i 3.5 i 3.5 Fluorescent Brightening Agent (parts by — 0.02 0.020.02 0.02 weight) Ultraviolet Absorber (parts by weight) 1.0 1.0 1.0 1.01.0 Total Light Transmittance (%) 54 56 55 54 70 Average Brightness(cd/m²) 5,500 5,600 5,600 5,500 5,700 Brightness Non-uniformity (%) 9191 92 92 92 Diffusibility ◯ ◯ ◯ ◯ ◯ Change in Brightness Non-uniformity◯ ◯ ◯ ◯ ◯ Heat Resistance ◯ ◯ ◯ ◯ ◯Ex.: Examplei: PARAROID EXL-5136 of Rohm & Haas (average particle diameter: 7 μm)ii: TOSPAL 120 of GE Toshiba Silicones (average particle diameter: 2 μm)Ultraviolet Absorber: 2,2′-p-phenylenebis(3,1-benzoxazine-4-one)

Examples 21 to 24

In the above Examples 16 to 20, 0.05 parts oftris(2,4-di-t-butylphenyl)phosphite, 0.01 parts ofoctadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate and 0.03 parts ofpentaerythritol tetrastearate were added to the polycarbonate resinsobtained in Synthesis Examples 1 to 3. Then, to the resulting mixtures,a fluorescent brightening agent (KAYALIGHT OS of NIPPON KAYAKU KOGYOCO., LTD.) and 2,2′-p-phenylenebis(3,1-benzoxazine-4-one) as anultraviolet absorber whose amounts were adjusted to those shown in Table7 were added. The resulting mixtures were melt-extruded from a ventedextruder at an extruder temperature of 280 to 320° C. and a dietemperature of 290 to 330° C. with the degree of vacuum of the vent keptat 27 kPa so as to pelletize it. After the pellets were dried at 120° C.for 4 hours, a microprism stamper having a height of 50 μm was insertedinto a cavity having a size of 100 mm×100 mm×2 mm, and an opticalwaveguide was molded at a cylinder temperature of 330° C. and a moldtemperature of 117° C. The results of evaluations made on the obtainedoptical waveguide are shown in Table 7. TABLE 7 Fluorescent UltravioletBrightening PC Absorber Agent Light Guidability Brightness (parts by(parts by (parts by Average Brightness Non-uniformity Refractive weight)weight) weight) (cd/m²) (%) Index Ex. 21 A 100 1.0 0 5,900 95 1.60 Ex.22 B 100 1.0 0 5,700 95 1.62 Ex. 23 C 100 1.0 0 5,600 94 1.62 Ex. 24 A100 1.0 0.02 5,800 96 1.60Ex.: Example

1. A polycarbonate copolymer (A) which comprises an aromatic dihydroxycomponent, the aromatic dihydroxy component comprising 5 to 95 mol % offluorene-skeleton-containing dihydroxy compound (1) represented by thefollowing general formula [1]:

 (wherein R¹ to R⁴ are each independently a hydrogen atom, a hydrocarbongroup with 1 to 9 carbon atoms which may contain an aromatic group, or ahalogen atom.), and 95 to 5 mol % of dihydroxy compound (2) representedby the following general formula [2]:

 (wherein R⁵ to R⁸ are each independently a hydrogen atom, a hydrocarbongroup with 1 to 9 carbon atoms which may contain an aromatic group, or ahalogen atom, and W is a single bond, a hydrocarbon group with 1 to 20carbon atoms which may contain an aromatic group or an 0, S, SO, SO₂, COor COO group.), the content of fluorene-9-one in the polycarbonatecopolymer being not higher than 15 ppm.
 2. The copolymer of claim 1,wherein the content of fluorene-9-one in the polycarbonate copolymer isnot higher than 5 ppm.
 3. The copolymer of claim 1, comprising anaromatic dihydroxy component comprising 15 to 85 mol % of thefluorene-skeleton-containing dihydroxy compound represented by thegeneral formula [1] and 85 to 15 mol % of the dihydroxy compound (2)represented by the general formula [2].
 4. The copolymer of claim 1,wherein the fluorene-skeleton-containing dihydroxy compound representedby the general formula [1] is 9,9-bis(4-hydroxyphenyl)fluorene or9,9-bis(4-hydroxy-3-methylphenyl)fluorene.
 5. The copolymer of claim 1,wherein the dihydroxy compound represented by the general formula [2] isat least one selected from the group consisting of2,2-bis(4-hydroxyphenyl)propane,2,2-bis(4-hydroxy-3-methylphenyl)propane,α,α′-bis(4-hydroxyphenyl)-m-diisopropylbenzene and1,1-bis(4-hydroxyphenyl)cyclohexane.
 6. The copolymer of claim 1,showing a b value of 5.0 or less when a solution prepared by dissolving5 g of the copolymer in 50 ml of methylene chloride in a light blockingcondition is measured at an optical path length of 30 mm.
 7. Thecopolymer of claim 1, having a sulfur compound content of not higherthan 50 ppm in terms of sulfur atom.
 8. The copolymer of claim 1, havinga chlorine content of not higher than 10 ppm based on terminalchloroformate groups and a terminal hydroxyl group (OH) content of nothigher than 250 ppm of the copolymer.
 9. A production method of thepolycarbonate copolymer of claim 1, comprising subjecting thefluorene-skeleton-containing dihydroxy compound (1) represented by thegeneral formula [1] and the dihydroxy compound (2) represented by thegeneral formula [2] to a polymerization reaction in an organic solventin the presence of phosgene and an acid binding agent, wherein thepolymerization reaction is carried out substantially in the absence ofmolecular oxygen.
 10. A polycarbonate composition comprising: A) 100parts by weight of polycarbonate copolymer (A), and B) 0.01 to 5 partsby weight of ultraviolet absorber (B), the polycarbonate copolymer (A)comprising an aromatic dihydroxy component, the aromatic dihydroxycomponent comprising 5 to 95 mol % of fluorene-skeleton-containingdihydroxy compound (1) represented by the following general formula [1]:

 (wherein R¹ to R⁴ are each independently a hydrogen atom, a hydrocarbongroup with 1 to 9 carbon atoms which may contain an aromatic group, or ahalogen atom.), and 95 to 5 mol % of dihydroxy compound (2) representedby the following general formula [2]:

 (wherein R⁵ to R⁸ are each independently a hydrogen atom, a hydrocarbongroup with 1 to 9 carbon atoms which may contain an aromatic group, or ahalogen atom, and W is a single bond, a hydrocarbon group with 1 to 20carbon atoms which may contain an aromatic group or an O, S, SO, SO₂, COor COO group.), the content of fluorene-9-one in the polycarbonatecopolymer being not higher than 15 ppm.
 11. The composition of claim 10,wherein the ultraviolet absorber (B) is uniformly dispersible in thepolycarbonate copolymer (A) and is stable under melt molding conditionsof the copolymer (A).
 12. The composition of claim 10, wherein when anamount of change in Yellow Index (YI) after a 2-mm-thick molded plateformed from the polycarbonate copolymer (A) is exposed to a mercury lampof 300 to 400 nm with an exposure intensity of 15 mW/cm² for 7 days isΔYI₀, a change in Yellow Index after a 2-mm-thick molded plate formedfrom the polycarbonate resin composition comprising the polycarbonatecopolymer (A) and the ultraviolet absorber (B) is exposed to a mercurylamp of 300 to 400 nm with an exposure intensity of 15 mW/cm² for 7 daysis ΔYI₁, and the degree (R_(YI)) of light resistance improving effect bythe ultraviolet absorber (B) is expressed as R_(YI)=(1−ΔYI₁/ΔYI₀)×100(%), R_(YI)≧50% holds.
 13. The composition of claim 10, wherein theultraviolet absorber (B) is an ultraviolet absorber showing anabsorbance (A_(360 nm)) at 360 nm measured at an optical path length of1 cm of not lower than 0.5 when dissolved in methylene chloride at aconcentration of 10 mg/L and an absorbance (A_(400 nm)) at 400 nmmeasured at an optical path length of 1 cm of not higher than 0.01 whendissolved in methylene chloride at a concentration of 10 mg/L.
 14. Thecomposition of claim 10, wherein when the glass transition temperatureof the polycarbonate composition containing 2 parts by weight of theultraviolet absorber (B) based on 100 parts by weight of thepolycarbonate copolymer (A) is Tg′ and the glass transition temperatureof the polycarbonate copolymer (B) containing no ultraviolet absorber(B) is Tg, Tg is 150° C. or higher and satisfies Tg−Tg′≦5° C.
 15. Thecomposition of claim 10, wherein the ultraviolet absorber (B) is abenzotriazole, benzophenone, triazine or benzoxazine based ultravioletabsorber.
 16. The composition of claim 10, wherein the ultravioletabsorber (B) is a benzoxazine based ultraviolet absorber represented bythe following general formula [3]:

(wherein R⁹ to R¹¹ each independently represent a hydrogen atom, ahydrocarbon group with 1 to 9 carbon atoms which may contain an aromatichydrocarbon group or a halogen atom, Ar represents a q-valent aromatichydrocarbon group having 6 to 15 carbon atoms, and q represents aninteger of 1, 2 or 3.)
 17. A molded article formed from thepolycarbonate copolymer (A) of claim
 1. 18. A film or sheet formed fromthe polycarbonate copolymer (A) of claim
 1. 19. A molded article formedfrom the polycarbonate composition of claim
 10. 20. A film or sheetformed from the polycarbonate composition of claim
 10. 21. A light-proofmolded article comprising a molded article formed from the polycarbonatecopolymer (A) of claim 1 and a layer comprising a polymer compositioncontaining an ultraviolet absorber, the layer being formed on the moldedarticle.
 22. A composite film or sheet comprising a film or sheet formedfrom the polycarbonate copolymer (A) of claim 1 and a layer comprising apolycarbonate composition containing an ultraviolet absorber, the layerbeing laminated on one or both surfaces of the film or sheet.
 23. Alight diffusing plate formed from a polycarbonate composition comprising99.7 to 80 parts by weight of the polycarbonate copolymer (A) of claim 1and 0.3 to 20 parts by weight of transparent fine particles.
 24. Thelight diffusing plate of claim 23, wherein the polycarbonate compositionfurther contains 0.01 to 5 parts by weight of the ultraviolet absorber(B) based on 100 parts by weight of the polycarbonate copolymer (A). 25.The light diffusing plate of claim 23, wherein the polycarbonatecomposition further contains 0.0005 to 0.1 parts by weight offluorescent brightening agent based on 100 parts by weight of thepolycarbonate copolymer (A).
 26. The light diffusing plate of claim 23,wherein the transparent fine particles have an average particle diameterof 1 to 30 μm.